It is well known that blends of elastomers containing polar groups such as acrylonitrile-butadiene copolymers (NBR) are not compatable with hydrocarbon rubbers such as ethylene-propylene rubbers. It is possible, however, to blend nitrile rubbers with certain polar resins such as styrene acrylonitrile; see for example U.S. Pat. No. 2,439,202. Blends of nitrile rubbers with acrylonitrile/butadiene/styrene resins (ABS) have been prepared; see for example Japanese Pat. No. S-7-5013369. These blends have also been prepared incorporating a third component such as polyvinylchloride (PVC); see for example U.S. Pat. No. 3,629,050.
Graft polymers of ethylene propylene terpolymers (EPDM) wherein the third monomer is a non-conjugated diene (EPDM) have been prepared wherein the graft polymer comprises styrene acrylonitrile resins (SAN). These grafts of SAN on an EPDM backbone are known as EPAS and are elastomeric in character when the resin side chain represents less than 60% by weight of the EPAS. EPAS has been successfully blended with SAN to prepare weather resistant, impact resistant resins; see for example U.S. Pat. Nos. 3,489,821 and 3,489,822.